Means for controlling machines



April 9 5- H. H. GEFFCKEN EIAL 1,998,132

MEANS FOR CONTROLLING MACHINES Filed July 25, 1930 Fig.1

Amok/ a 9 75 I: 7% l l l+--l 1 74- 7 22 I T 2/ 2 24 y 2o 79 I 26 lnvenfors: Heinn'c/z Hermann Gf/Z/ren Hans Rudolf Pichler W latented Apr. 16, 1935 PATENT OFF! MEANS FOR CONTROLLING MACHINES Heinrich Hermann Geifcken and Hans Rudolf Richter, Leipzig, Germany, assignors to Radio Patents Corporation, New York, N. Y., a corporation of New York Application July 25, 1930, Serial No. 470,691 In Germany August 10, 1929 ll Claims.

In machine engineering, more especially in the case of counting, sorting and paper-making machines, the necessity often arises of releasing or interrupting the operation at marked points of the work or of a parallel running pattern, or the like. In order to replace the operation by hand by an automatic operation, it has already been proposed to use for this purpose light-sensitive devices (photo-electric cells, selenium cells, or the like).

The invention relates to the construction of a detail in such machines which will greatly improve its operation and reliability. However, as the invention can only be perceived by considering the whole of the operation of the machines, we will first of all describe the operation by a reference to a simplified arrangement and then refer to the subject matter of the invention.

Let us assume that the problem is to count those card-index cards which are provided at the edge with a mark in the form of a black line. For this purpose the cards (I) are arranged close to one another and are transmitted by means of an automatic device on to the running belt (2) which moves at a constant speed under the lightsensitive device (4). The latter consists of a lamp (5), the rays of which are condensed by means of a lens (6) and are transmitted in a known manner through an annular photo-electric cell ('1) to the edges of the card-index cards (l) where they produce at (3) the sharp image of the incandescent filament of the lamp (5). From the card-index cards the incident rays are refiected in a difiused manner and they partly reach the photo-electric cell (7), in which they produce a current. However, as soon as the dark mark provided on the individual card-index cards, comes in the position 8, the reflected amount of light suddenly drops to a fraction of its normal value and there is produced a corresponding fluctuation of current in the electric circuit of the photo-electric cell (7). This current fluctuation operates the relay (ill) by means of the transmission apparatus (9) (amplifier or the like), which relay moves the counting mechanism (l I) forward one tooth. This turning of the counting mechanism constitutes in the present case the operation. However, the principle of the machine is not substantially changed when the relay (ID) merely closes a circuit l2), which controls a sorting device, which sorting device moves the card down from the conveying band (2), or a punch which perforates the card, or some other similar mechanism. Further, instead of the control being released by the cards with their dark lines, the same may be released by banknotes or the like with their watermarks, by cloth webs with their weaving faults, or paper piles with their impressions.

Difiiculties have been encountered in the construction of the machine hereinbeiore referred to as regards the transmission apparatus (9). As is well known, the electrical properties of most light-sensitive electric devices are not very constant and the normal current which fiows through them with an average illumination as well as the sensitiveness with which they react to a fluctuation in the illumination, are always subject to certain temporary fluctuations. Similarly, the source of light (5) cannot be considered to be permanently constant as its illumination is subject to periodic fluctuations as well as to temporary variations. However, the most disturbing effects are the variations of the general illumination (difiused day-light, or the like), which variations act on the light-sensitive electric device and which can be avoided only by the photo-electric device being enclosed in a lighttight manner. Moreover, a corresponding subsequent adjustment is necessary with the transmission apparatus hitherto employed when a kind of cards of different reflection capacity or of different colour is inserted in the apparatus.

All these disadvantages are avoided by the arrangement according to the present invention. The invention consists in that within the said transmission device (9), between the circuit of the light-sensitive device (1) and the circuit of the relay (ill) controlled by the latter, there is inserted an electrical member (transformer condenser, or the like) which allows only an alternating current to pass through. In this way slow current variations of very small di/dt, which may be caused by variations in the light-sensitive electrical device (1), by the variation in the illumination of the illuminating lamp (5), by variation of the difiused day-light or the like, are without any influence upon the working mechanism (ID, ll). Further, no subsequent adjustment is necessary when bodies having a different refiection capacity or a different colour are inserted into the machine, since the strength of the local current flowing through the circuit of the lightsensitive device (7) is rendered practically negligible by the present invention and only the steep current variation which is produced when a mark enters the illumination field (8) can, owing to its alternating current character, pass through the transmission member which allows only alternating currents to pass through and act upon the working mechanism (10, II) or the relay controlling it.

Further difliculties which have been experienced in the operation of .devices of the above and similar type were due to the fact that the current impulses supplied by the photoelectric cell or similar controlling device were insuflicient both in intensity and duration to operate a relay or other translating device. As is understood, a relay possesses mechanical and electrical inertia which has to be overcome by a sufiiciently strong impulse. In the prior arrangements, large and expensive amplifiers were necessary to increase the current intensity to an amount sufilclent for safe operation of a relay or other trans iating device.

In order to overcome the above disadvantages and dificulties, the present invention in accordance with a further object and feature provides a novel arrangement and method for amplifying the available controlling energy by increasing the length of the weak and short control current impulses in such a manner thatby the use of a single amplifying tube sufiicient output energy variation is obtained to operate a relay or similar translating device.

The invention will now be more fully described with reference to Figure 2. The selenium cell (I3), which is used as the light-sensitive device, is connected in series with the source of current (96) and the protective resistance (I5). The relay (I6) which is used for the control of the working mechanism (It), I I) in Figure 1, is not inserted directly in the circuit of the selenium cell (l3) as has hitherto been usual but is connected therewith through the intermediary of a transformer (H). The relay (I6) is constructed in the form of the known trap-boards as a drop relay, so that in the case of a very short current impulse it closes with certainty the working circuit (I8). By means of a mechanical device (not shown) it can be ensured that after each operation (counting, sorting out, or the like) the relay will be automatically returned into its responding position (shown in the drawing).

It will be seen that slow current variations in the circuit of the light-sensitive device will not be able to induce a current in the secondary winding of the transformer (H), in which the relay (I5) is inserted whilst quick current variations as may be produced by a sudden throwing of a shadow upon the selenium cell (l3) will cause the relay (It) to respond with certainty.

It has been found advantageous in practice to subject the light-sensitive device (1, E3) to a current load of normal illumination which shall be as small as possible in order to increase its life. In that case however, amplification is necessary. According to the invention, the amplification can be secured in an especially advantageous manner whilst at the same time the alternating current amplitudes which occur are separated fromthe normal continuous current of the light-sensitive device by providing a condenser in the connection to the grid of a thermionic tube whereby only alternating current is allowed to pass through. It has been found that in this manner it is possible to obtain a sufiicient control of the grid of the thermionic tube also in the case of very weak currents which are no longer properly transmitted by a. trans- I former.

is connected in series with the high ohmic resistance (it) on to the source of current (20). The point of connection (2!) between them is connected to the plate of a condenser (22), the other plate of which is connected to the grid (23) of the thermionic tube (25). At the same time the grid (23) is connected over the high resistance (25) to the negative pole of the battery and it thus receives a bias. The circuit of the thermionic tube (24) includes the relay (2?) which corresponds to the relay (I6) illustrated in Figure 2, so far as its purposeis concerned. Connections which are similar to the connection illustrated in Figure 3 are known in the radio art as an audion, being used for the purpose of rectification of high frequency current. The object and the operation, however, are difierent in the present case.

As no conducting connection is provided between the point (2|) and the grid of the thermionic tube (24) the grid is entirely unafiected by low voltage variations of the said point-as may be produced by slow current variations in the photo-electric cell (1). The grid thus retains the grid bias, which is imparted to it by the battery (25), with respect to the incandescent filament. However, as soon as a sudden current variation occurs in the circuit of the photoelectric cell (5), a corresponding voltage variation is produced at the point (2|), which variation is fully transmitted to the grid (23) since the resistance (25) is too high to effect an immediate leaking off of the charge. In consequence thereof, the electronic current of the tube (24) is influenced in a known manner and the relay (27) responds. Instead of the relay (27) being inserted directly in the anode circuit of the tube (25), the same may be arranged in the anode circuit of a second tube connected in cascade with the first tube.

In some cases, the grid resistance (25) may be extremely high (IO-I00 megohms) and then a throttling of the tube (24) is obtained which lasts for some time. In this case, in addition to a current amplification being obtained, a very great increase in output is obtained by considering the time factor of the grid condenser (23) and grid leak (25) combination (long-lasting throttling of the tube) (24). v

What we claim is:-

1. In an electrical system comprising a vacuum tube having cathode, anode, and grid electrodes; means including a grid condenser and a grid leak resistance for applying a control impulse potential to said grid; a relay device in the anode circuit of said tube; said grid leak resistance being of extremely high value to produce a prolonged choking of said tube by a sudden control impulse for increasing the output energy and operating said relay.

2. In an electrical'system as described in claim 1,-in which said leak resistance has a value of 10 to megohms.

3. -In an electrical system comprising a vacuum tube having cathode, anode, and grid electrodes; means including a grid condenser and grid leak resistance for said tube for applying a control impulse potential to said grid; a mechanical relay in the anode circuit of saidtube; said grid leak resistance having an extremely high value to produce a prolonged choking of said tube to increase the output energy and to insure operation of said relay by control impulses applied to said grid condenser.

4. In an electrical system comprising a vacuum tube having cathode, anode, and grid electrode; a photoelectric cell; means including a grid condenser and grid resistance for said tube for applying a control impulse potential from said cell to said grid; a mechanical relay connected in the output circuit of said tube, said grid leak hav ing a value of from 10 to megohms to secure a prolonged choking of said tube by a sudden control impulse potential lasting for an extended period to increase the output energy and operate said relay.

5. In an electrical system as described in claim 4, in which said photoelectric cell is arranged in series with a resistance and a connection from the common terminal of said cell and said resistance a to said grid condenser.

6. In an electrical system, in combination, a

'relay, means for operating said relay by a control serted in the anode circuit of said tube, a condenser having one plate connected to said grid, means including circuit connections for applying the control impulse potential to the opposite plate of said condenser, and grid leak means for said tube of extremely high value to produce a prolonged choking effect of said tube by a relatively short control impulse for increasing the output energy variation to operate said relay.

7. In. an electrical circuit, in combination, a relay, means for operating said relay by a control impulse potential normally too short to energize said relay, comprising an electron tube having a cathode, a grid and an anode, said relay being connected in the anode of said tube, a'condenser having one plate thereof connected to said grid, means including circuit connections for applying a control impulse to the opposite plate of said condenser, and grid leak means of the order of from 10 to 100 megohms for said tube to produce a prolonged choking effect of said tube by a relatively short control impulse for increasingthe output energy variation to operate said relay.

8. An electrical system, in combination, a relay; a photoelectric device producing control impulse potentials in accordance with sudden light variations normally insufllcient for energizing said relay, means for operating said relay comprising an electron tube having a cathode, a grid and an anode, said relay being connected in the anode circuit of said tube, a condenser having one plate thereof connected to said grid, means including circuit connections for applying said control impulse potential to the opposite plate of said condenser, and grid leak means for said tube of a value of 10 to 100 megohms to produce a prolonged choking of said tube for increasing the output energy variation to operate said relay.

9. An electrical system, in combination, a relay; a photoelectric device subjected to short light variations producing Weak and short current impulses normally insumcient to energize said relay; an electron tube having a cathode, grid and anode, a source of current supply for said tube, said relay being connected in the anode circuit of said tube; an impedance means; said impedance means, said photoelectric device and said source being connected to form a closed circuit; a condenser having one plate thereof connected to the grid of said tube; a connection from the junction of said impedance means and said photoelectric device to the opposite plate of said condenser, and a grid leak resistance for said tube of a value of 10 to 100 megohms to produce a prolonged choking of said tube by a potential output energy variation of said tube to operate said relay.

10. In combination with an electrical system, a relay; means for operating said relay by a control impulse potential being normally of insufiicient intensity and duration to effect operation comprising an electron tube having a cathode, grid and an anode; means for producing an electric charge on said grid by a control potential impulse, further means for maintaining said charge for a sufllcient period thereby choking said tube and increasing the output energy variation for operating said relay.

11. In an electrical system, a translating device, means ior transforming current impulses normally of too short duration and too weak to operate said translating device into amplified impulses of extended duration comprising a vacuum tube having a cathode, grid and an anode, said translating device being connected in the anode circuit of said tubes, means for converting a controlling impulse into an electric charge on said grid, further means for maintaining said chargefor a suflicient period to efiect prolonged choking of said tube for increasing the intensity and duration 01' the energy variation in the anode circuit of said tube. 

